The present invention relates to cutting devices, and more particularly to cutting methods and apparatus for severing sheet material from a roll.
Paper and other materials are conveniently stored in rolls, from which the user can cut or tear off a piece of the desired length. For example, a roll of paper may be mounted on a shaft and a weighted bar is then hingedly mounted on the shaft to allow the user to tear paper from the roll by pulling the paper upwardly against the bar. The bar, however, must be heavy enough to apply sufficient force to tear the paper, because once the bar is raised from the roll, the paper is free to unwrap from the roll and the tearing operation will be uneven or incomplete.
Prior attempts to provide a reliable paper cutting device have produced various devices which were bulky and/or fairly complex. Several of those prior devices required the paper to be threaded from the roll through one or more slots or grooves in the paper cutter in order to tear the paper against a blade. Other mechanisms had bearings upon which the cutter rotated which bearings required lubrication. In general, the known devices of the prior art did not assure a straight, even cut of the paper, particularly when the paper roll was out of round or had diminished appreciably in diameter due to the withdrawal of a large quantity of paper from the roll.
One such known device is disclosed in U.S. Pat. No. 423,228 issued on Mar. 11, 1890 to Ellerman and includes a roll paper holder and cutter including a bulky gravity bar. The gravity bar is carried on a pair of parallel standards provided on either side of the roll of paper. A cutting bar is carried ahead of the paper roll. To tear the paper with the Ellerman device, the paper is pulled against the stationary cutting bar, which bar is apparently not permitted to tilt about the pair of parallel standards.
Another known cutting device is disclosed in U.S. Pat. No. 2,655,214 issued on Oct. 13, 1953 to Van Cleef. The Van Cleef device includes a tape cutter member which is constrained to ride along the outer surface of a roll of tape by an elastic member. In order to tear the tape, a portion of the tape cutter member must be manually held against the tape roll. A channel is provided along the rearward edge of the tape cutter member to provide a flat surface against the tape when the cutter is pressed down.
A further example of a known paper cutter is disclosed in U.S. Pat. No. 436,789 issued on Sept. 23, 1890 to Jobes. The Jobes device includes a roll paper cutter having a cutting edge which is pivotably mounted with respect to the roll of paper. In the Jobes device, a number of various stops and adjustments are provided to adapt the cutter to different sized rolls.
A still further example of a known paper cutter may be seen in U.S. Pat. No. 2,234,818, which issued on Mar. 11, 1941 to Bulman. The Bulman paper cutter includes a cutter bar which is firmly held against a roll of paper, even when tearing the paper, by a pair of springs.
Other known cutting devices are disclosed in the following U.S. Pat. Nos.: 1,928,148 issued Sept. 26, 1933 to Bratz; 851,832 issued Apr. 30, 1907 to Patterson; and 389,506 issued Sept. 11, 1888 to Haiman.
Accordingly, it is an object of the present invention to provide a cutting device which is both relatively simple to use and inexpensive to produce.
It is a further object of the present invention to provide a one piece cutter bar which will ride freely along a roll of paper while the paper is being withdrawn from the roll but which will firmly lock in place when the paper is to be cut.
Still a further object of the present invention is to provide a cutting device which is easily installed or removed from an operative position.
Yet another object of the present invention is to provide a cutting device which aids in preventing further rotation of the roll as the paper is torn therefrom.
These and other objects are realized with a paper cutting device according to the present invention wherein an elongate cutter bar is provided with a cutting blade fixed to a leading edge of the cutter bar. An opening is disposed at each end of the cutter bar. Each opening receives an upright post therein. An upstanding projection is provided along the cutter bar to frictionally engage the two upright posts.
According to a further feature of the present invention a paper roll stand is provided to support the paper roll and the upright posts.
According to a preferred embodiment of the present invention, the cutter bar is provided with a curved channel along the trailing edge of the cutter bar to continually contact the paper roll.
According to a further feature of the present invention the openings comprise notches each having a diameter which is slightly larger than the diameter of the upright posts.
In order to tear paper from the roll, a predetermined length of paper is withdrawn and lifted, beginning at one end of the paper roll and continuing along the roll to the other end, against the cutting blade. The upward force applied by the paper pivots the cutter bar about the channel until the upstanding rib and the rear side of the notches clamp the cutter bar about the upright posts. The pivoting motion of the cutter bar also tends to drive the channel into the paper roll to retard the roll from further rotation while the paper is torn. The cutter bar is maintained in constant contact with the paper roll by the force of gravity as the paper is withdrawn from the roll. Even if the paper roll is non-circular, the roll of paper will lift the curved channel along the trailing edge. In this way, the cutter will assume a more tangential attitude on the roll and will permit the cutter to raise or lower on the upright posts as necessary. Of course, when the diameter of the paper roll has decreased sufficiently, the trailing edge of the cutter may extend beyond the roll of paper.